Walnut Flashcards
Which are the three most important countries for walnut production in the world?
China 43%, USA 17%, Iran 11%.
Which are the most important species for walnut cultivation?
Juglans regia
Juglans hindsii
What are the names of female and male flowers in walnut?
Male: Catkins Female: Pistillate
Why are pollenizers needed for some walnut cultivars?
Due to strong proterandry, female blooming happens later than male blooming, requiring more than one cultivar in the orchard.
What causes Pistillate Flower Abortion (PFA) and which cultivar is most sensitive to it?
Excess pollination decreases fruit set; Serr is the most sensitive cultivar.
What is the difference between terminal and lateral bearing cultivars in walnuts?
Terminal: bearing bud only at the shoot’s apex; Lateral: bearing buds on lateral shoots.
What are some important walnut cultivars and their characteristics?
Noce di Sorrento: Terminal bearing, early leaf out, high shelling %.
Franquette: Terminal bearing, late leaf out, good quality, strong proterandry.
Chandler: Lateral bearing, early flowering, large size.
Hartley: Highly productive, late bearing, sold in shell.
What are the available rootstocks for walnut and their criteria for selection?
English walnut: tolerant to blackline disease.
Black walnut: tolerant to water excess and salinity.
Paradox: tolerant to lime, Phytophthora, heavy soil.
Criteria: soil tolerance and disease sensitivity.
What are the limits to the diffusion of walnut in cold climates?
Cold hardiness: -15°C buds, frost tolerance: 0°C bursting buds, sensitive to spring and autumn frost.
What is the range of planting distances in walnut orchards?
8 by 8 meters to 10 by 10 meters.
What are the training systems used for walnut trees?
Vase / pyramid
What pruning technique is used for walnut trees?
Fully mechanized heading cuts to increase lateral shoot formation and improve the number of fruiting branches.
What factors define the timing of walnut harvesting?
Hull split and visible nut, kernel color, and incidence of navel worm.
How is nut bleaching performed and why?
Bleaching is done to remove the dark part of the shell using sulfur dioxide or potassium permanganate (formerly chloroform).
